A MODEL FOR THE FORMATION OF THE SATELLITE SYSTEMS OF JUPITER, SATURN, AND NEPTUNE

The evolution of the density of the circumplanetary disks around Jupit er, Saturn, and Neptune as a result of accretion of planetesimals from heliocentric orbits is numerically studied within the context of the planar-circular three-body problem. More than a million trajectories o f particles after collisions are analyzed. Regions of particles with r etrograde motion are shown to be formed in an initially prograde proto satellite disk. These regions are nicely exemplified by the well-known retrograde satellites: the Pasiphae group, Phoebe, and Triton.